POWDER DISTRIBUTION SYSTEM FOR THREE-DIMENSIONAL PRINTER
The present invention relates to powder-layer three-dimensional printers ( 2 ) having a discrete supply hopper ( 340 ) and a recoater ( 20 ). The discrete supply hopper ( 340 ) is configured to transfer a build powder to the recoater ( 20 ) in a manner that enhances the uniformity of build powder layers that are dispensed from the recoater ( 20 ). In some embodiments, at least one of the discrete supply hopper and the powder hopper of the recoater is adapted to selectively contact the other, seal against the other, and/or have one partially inserted inside the other so as to diminish or prevent powder pluming during the transfer of build powder from the discrete supply hopper to the recoater.
1 . A powder-layer three-dimensional printer comprising:
a recoater having a sheet screen having a plurality of perforations and a first side and a second side, an ultrasonic transducer adapted to vibrate the sheet screen, and a hopper adapted to provide a build powder to a first side of the sheet screen, wherein when the ultrasonic transducer vibrates the sheet screen the build powder from the hopper is dispensed from the sheet screen second side via the perforations.
2 . The powder-layer three-dimensional printer of claim 1 wherein,
when the ultrasonic transducer vibrates the sheet screen the build powderfrom the hopper is dispensed from the sheet screen second side via the perforations as build powder pellets.
3 . The powder-layer three-dimensional printer of claim 1 wherein, the hopper is adapted to provide mass flow of the build powder to the sheet screen first side.
4 . The powder-layer three-dimensional printer of claim 1 wherein, the hopper comprises a lower portion proximate to the sheet screen and an upper portion, the lower and upper portions being interconnected to form a continuous reservoir.
5 . The powder-layer three-dimensional printer of claim 1 further comprising, a sheet screen holder, the sheet screen holder having first and second sides and an aperture extending therebetween, wherein the sheet screen is attached to the sheet screen holder so that at least some of the perforations of the sheet screen are in fluid communication with the aperture.
6 . The powder-layer three-dimensional printer of claim 5 wherein, the sheet screen is bonded to the sheet screen holder by an adhesive.
7 . The powder-layer three-dimensional printer of claim 1 wherein, the sheet screen second side is positioned at an angle of between 20 and 70 degrees to the horizontal.
8 . The powder-layer three-dimensional printer of claim 1 wherein, the ultrasonic transducer is positioned at an angle to the horizontal so as be able to apply to the sheet screen a vibration having both a horizontal component and a vertical component.
9 . The powder-layer three-dimensional printer of claim 1 wherein, the ultrasonic transducer is adapted to sweep across a frequency range during its operation.
10 . The powder-layer three-dimensional printer of claim 1 wherein, at least one of the size, shape, and distribution of the perforations of the sheet screen is varied to reduce any tendency the recoater otherwise would have to dispense build powder non-uniformly due to local vibration variances.
11 . The powder-layer three-dimensional printer of claim 1 wherein, at least one of the perforations has a hole shape which includes at least one tine.
12 . The powder-layer three-dimensional printer of claim 1 further comprising, a trolley adapted to carry the recoater.
13 . The powder-layer three-dimensional printer of claim 1 wherein, the recoater further comprises at least one of a smoothing device, a drying device, and a curing device.
14 . The powder-layer three-dimensional printer of claim 1 further comprising, a housing enclosing a space having a gaseous atmosphere, a horizontally disposed deck dividing the space into an upper section and a lower section, a build box positioned proximate to the deck and at least in part of the space upper section, a plurality of passageways through the deck located so as to surround the build box and providing fluid communication between the space upper and lower sections, a plenum located in the space lower section and in fluid communication with the passageways, an exhaust duct in fluid communication with the plenum, and a dust collection unit located outside of the housing and including a controllable vacuum source and a filter both in fluid communication with the exhaust duct, wherein when the vacuum source is operated at least some of the gas of the gaseous atmosphere in the space upper portion is drawn through the passageways and through the filter.
15 . The powder-layer three-dimensional printer of claim 14 further comprising, a shroud surrounding the build box and forming therebetween an annulus, the annulus providing fluid communication between the space upper section and the passageways.
16 . The powder-layer three-dimensional printer of claim 14 wherein, the housing has at least one vent providing fluid communication between the gaseous atmosphere in the space upper section and an atmosphere outside of the housing.
17 .- 32 . (canceled)
33 . The powder-layer three-dimensional printer of claim 1 wherein, the recoater further comprises a drying device.
34 . The powder-layer three-dimensional printer of claim 1 wherein, the recoater further comprises a curing device.